940.01. First-degree intentional homicide
(1) Offenses. (a) Except as provided in sub. (2), whoever causes the death of another human being with intent to kill that person or another is guilty of a Class A felony.
(b) Except as provided in sub. (2), whoever causes the death of an unborn child with intent to kill that unborn child, kill the woman who is pregnant with that unborn child or kill another is guilty of a Class A felony.
(2) Mitigating circumstances. The following are affirmative defenses to prosecution under this section which mitigate the offense to 2nd-degree intentional homicide under s. 940.05:
(a) Adequate provocation. Death was caused under the influence of adequate provocation as defined in s. 939.44.
(b) Unnecessary defensive force. Death was caused because the actor believed he or she or another was in imminent danger of death or great bodily harm and that the force used was necessary to defend the endangered person, if either belief was unreasonable.
(c) Prevention of felony. Death was caused because the actor believed that the force used was necessary in the exercise of the privilege to prevent or terminate the commission of a felony, if that belief was unreasonable.
(d) Coercion; necessity. Death was caused in the exercise of a privilege under s. 939.45(1).
(3) Burden of proof. When the existence of an affirmative defense under sub. (2) has been placed in issue by the trial evidence, the state must prove beyond a reasonable doubt that the facts constituting the defense did not exist in order to sustain a finding of guilt under sub. (1).